William M. Miley was born at Fort Mason in California, to Sara Miley and Lieutenant Colonel John D. Miley (for whom Fort Miley Military Reservation was named). His family had a long history of military service, with three generations before him serving in the United States Army. Two great-grandfathers, his grandfather, his father, his great-uncle, his uncle and his son all graduated from the United States Military Academy (USMA) at West Point, New York.
Following the war, Miley held a series of assignments, including as a professor of military science at what was then Mississippi State College, in Starkville, Mississippi. It was during this time that he met and married his wife, Julia Sudduth. Other assignments included serving as athletic director at West Point, and infantry assignments in Panama, the Philippines, and at Fort Sam Houston.
In April 1943, Miley organized the activation of the 17th Airborne Division at Camp Mackall, North Carolina. He was the sole commander of the 17th Airborne Division during the war, leading the division through such actions on the Western Front as the Battle of the Bulge and Operation Varsity. The division was deactivated in late 1945, but reactivated briefly in 1948 as a training unit.
Following his retirement from the army in 1955, Miley worked for Merrill Lynch, Pierce, Fenner & Beane, until his retirement in 1976, at which time he returned to Starkville, Mississippi. Miley was the second to last living division commander of World War II. He died in Starkville in September 1997 at the age of 99, three months short of turning 100. Only Major General Ralph C. Smith, who commanded the 27th Infantry Division during World War II, would live longer, passing away in January 1998 at the age of 104.